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From: sorgatz@ttidca.TTI.COM ( Avatar)
Newsgroups: comp.arch
Subject: Re: Benchmarking ...[really Compiler flames]
Message-ID: <787@ttidca.TTI.COM>
Date: Thu, 4-Jun-87 20:14:44 EDT
Article-I.D.: ttidca.787
Posted: Thu Jun  4 20:14:44 1987
Date-Received: Tue, 9-Jun-87 02:15:29 EDT
References: <410@winchester.UUCP> <3490003@wdl1.UUCP> <7261@amdahl.amdahl.com>
Reply-To: sorgatz@ttidcb.UUCP (Erik Sorgatz - Avatar)
Organization: Citicorp/TTI, Santa Monica
Lines: 50

Summary:people go to school for 4 years to code like this?

Keywords:compiler design, compiler designers


In article <7261@amdahl.amdahl.com> chuck@amdahl.UUCP (Charles Simmons) writes:
>
>The holistic approach suggests that you need to simulate the application
>environment on each system that you are considering buying.  This
>obviously has a number of difficulties associated with it.  Perhaps
>the biggest difficulty is accurately determining what the application
>environment will actually look like.

This presumes that the applications designer should be given free reign to
do silly stuff. Far better would be to determine the performance of a system
based on the "raw" power of the machines attributes directly.

>
>The reductionistic approach suggests that system performance can
>be estimated by examining a number of pieces of the system.  In
>particular, I would suggest the following pieces:
>
{{many exellent categories}}

>3)  context switching speeds:  how long does it take for the system
>to process an interrupt?  how long does it take for the system to
>switch between user programs?

 This is mostly a measure of how directly the operating system can react to
the real-world events or interrupts, not something that UNIX is famous for
doing in an intellegent fashion.

>4)  compiler performance:  how well does the compiler optimize?
>how slow is the compiler?  how large are the binaries produced by
>the compiler?

 This is the central point: most compilers are dumb. They appear to have been
written by someone scarcely familar with the hardware environment. The classic
examples of 'jump-to-the-next-instruction' or 'save-all-registers/do-something-
non register-related/restore-all-registers' are the biggest wastes of MIPS
although some optimizers will nail these => 50% of the time.

>
>Any other reductionists want to help me out with my argument?
>
>-- Chuck

 Consider this to be my contribution: Wakeup compiler experts! Read the !@#$%^&
chip spec! Don't assume that your 'meta-pass-intermediate code generators
are going to produce efficient code; they dont!
-- 
-Avatar-> (aka: Erik K. Sorgatz) KB6LUY
Citicorp(+)TTI
3100 Ocean Park Blvd.   (213) 450-9111, ext. 2973
Santa Monica, CA  90405 {csun,philabs,randvax,trwrb}!ttidca!ttidcb!sorgatz